In spring, summer and fall, the majority of a chickadee’s diet consists of animal protein: moth and butterfly caterpillars (including early growth stages of gypsy moths and tent moths), other insects and their eggs and pupae, spiders, snails and other invertebrates. Chickadees also eat wild berries and the seeds of various plants including ragweed, goldenrod and staghorn sumac. Seeds and the eggs and larvae of insects are important winter staples. In the fall, chickadees begin storing food in bark crevices, curled leaves, clusters of pine needles, and knotholes. The birds rely on these hoards when other food becomes scarce. Chickadees also eat suet from feeding stations and fat and meat bits from dead animals.
In winter, chickadees live in flocks, generally comprised three to 12 birds made up of mated pairs as well as individuals. There is a social structure and hierarchy within these flocks with dominant pairs. Listen for the chick-a-deedee-dee calls that flock members use to keep in contact while foraging around a territory of 20 or more acres. A flock will defend its territory against other chickadee flocks. At night, chickadees roost individually in tree cavities or among dense boughs of conifers. A roosting bird tucks its head under a wing to conserve body heat. On cold nights, a chickadee’s body temperature drops as much as 20 degrees, causing the bird to enter a state of regulated hypothermia, which saves significant amounts of energy. Chickadees lose weight each night as their bodies slowly burn fat to stay alive. They must replace those fat stores by feeding the next day.
In spring, the winter flocks break up as pairs and claim nesting territories ranging from 3 to 10 acres in size. Chickadees nest in May and June. The usual site is a hole in a tree, excavated by both sexes. Birch is a favorite, because this tree’s tough outer bark stays intact after the inner wood rots and becomes soft enough for chickadees to excavate.
Chickadees also clear out cavities in pine, aspen, alder, willow, and cherry trees, and use abandoned woodpecker holes. The cavity is usually 4 to 10 feet above the ground. The female assembles the nest by laying down a base of moss, then adding softer material such as animal fur or plant fiber. House wrens compete for nest cavities and may destroy chickadee eggs and broods. Raccoons, opossums and squirrels raid nests. Chickadees will renest if a first attempt fails. Only one brood is raised per year. Chickadees will use nest boxes with small entrance holes (a diameter of 1¼ inch is recommended).
The five to nine eggs are white with reddish brown dots. The female incubates them, and the male brings her food. The eggs hatch between 11 and 13 days. Juveniles beg loudly and are fed by both parents. Young fledge 12 to 16 days after hatching. Three to four weeks after fledging, the young suddenly disperse, moving off in random directions. As winter approaches, they join feeding flocks. Some become “floaters,” moving between three or more flocks, ready to pair should another bird’s mate die.
Chickadees are taken by many predators including sharp-shinned hawks, American kestrels, Eastern screech owls, northern saw whet owls, and domestic and feral cats. Sometimes chickadees mob these enemies while sounding zee-zee-zee alarm calls. The average life span for a chickadee is roughly one and a half to two years, and the oldest known chickadee lived 12 years, five months. Every few years, long distance movements take place within the population. These “irruptions” may be launched by failure of seed crops or high reproductive success.
